In the rapidly advancing semiconductor manufacturing industry, CMOS, complementary metal oxide semiconductor, FinFET devices are favored for many logic and other applications and are integrated into various different types of semiconductor devices. FinFET devices typically include semiconductor fins with high aspect ratios and in which channel and source/drain regions of semiconductor transistor devices are formed. A gate is formed over and along the sides of the fin devices utilizing the advantage of the increased surface area of the channel and source/drain regions to produce faster, more reliable and better-controlled semiconductor transistor devices.
In FinFET and conventional planar transistor devices, a compressive stress applied to a PMOS device advantageously enhances hole mobility. Similarly, tensile stress applied to NMOS devices advantageously enhances electron mobility in the NMOS device. For planar CMOS devices, complex stressors such as selective SiGe source/drain structures are used to enhance hole mobility in PMOS devices and tensile contact etch stop layers, contact etch stop layer (CESL), or other dielectric film stressors are used to enhance electron mobility for NMOS devices to enhance overall device performance. The additional processing operations and costs associated with these techniques for enhancing hole and electron mobility are among the challenges associated with attempting to integrate these techniques into FinFET processing schemes.
FIG. 1A is an isometric view of a conventional finFET 100. The fins 106 comprise raised oxide defined (OD) regions 106 above a semiconductor substrate 101 (shown in FIGS. 1C, 1D). Fins 106 are separated from each other by a shallow trench isolation (STI) region 102, and are located between a pair of STI regions 102. The fins 106 have a step height 107 above the top surface of the STI regions 102. Polycrystalline silicon gate electrodes 108 are formed over the fins 106, with a thin gate dielectric layer (not shown) in between. Sidewall spacers 110 are formed on both sides of each gate electrode 110, for forming lightly doped drain (LDD) implant regions (not shown).
FIG. 1B shows one of the fins 106 after an epitaxial growth step raises the surface 106e of the fin 106. The top portion 106e of the fin 106 acquires an approximately pentagonal shape, with lateral extensions 106L that extend a distance 109 parallel to the direction of the top surface of the substrate 101.
FIGS. 1C and 1D show the X-direction (front) and Y-direction (side) elevation views of the finFET 100 of FIG. 1A, after formation of the silicon oxide hard mask 112 and dummy side wall spacers 110, but before the epitaxial SiGe formation.
FIGS. 1E and 1F show the X-direction (front) and Y-direction (side) elevation views of the finFET 100 of FIG. 1A, after performing epitaxial processing. An epitaxial process is performed on the fins 106, forming a SiGe layer 106e over the fin 106 of the finFET.
As shown in FIG. 1E, the epitaxial SiGe lateral extensions 106L of fin SiGe layers 106e extend laterally towards each other, reducing the window 106w between adjacent fin side extensions 106L.